1. Field of Invention
The present invention relates to a display apparatus which performs a display operation corresponding to display content of a button display portion when "on" data, showing that an operating surface is press-operated, is inputted. Coordinate data showing a touched position on the operating surface corresponds to a coordinate of the button display portion that is displayed on the display screen.
2. Description of Related Art
Vehicles, for example, are provided with a conventional display device with a touch operation function. One example of this display device is constructed to detect a touched position with respect to a display screen through an optical sensor. Specifically, light projecting elements and light receiving elements are arranged so as to form a plurality of parallel optical axes corresponding to vertical and horizontal directions of the display screen. By touching the display screen with a finger, some optical axes extending between the light projecting elements and the light receiving elements are blocked, a center position of the touched area is detected and the coordinate data is outputted.
Accordingly, when an air conditioner screen, for example, is displayed, it is possible to arbitrarily adjust the air conditioning function in the vehicle by touch-operating a button display portion which is displayed on the screen for the air conditioner. By using the display device with this type of touch operation function, it is possible to omit switches for devices on the vehicle, such as the air conditioner, a radio, or a car navigation system. Therefore, the instrument panel can look neat.
In the conventional display device with the touch operation function as described above, the driver is required to touch the display device by stretching his arm, thus rendering controllability of the display device insufficient. Therefore, separating the touch operation function from the display device has been considered. A touch operation information output device, that outputs coordinate data showing the finger-touched position on the operating surface and also outputs "on" data indicating that operating surface is press-operated, is disposed separately from the display device. The touch operation information output device is installed, for example, on the arm rest of the driver's side door so that it is possible to improve operability by the driver. However, because, for example, the button display portion of the map screen is displayed quite small without standing out, the button display portion is difficult to recognize even though operation is improved. Problems remain such that a user can select an erroneous button display portion by a touch operation of the touch operation information output device.
Furthermore, in order to select a button display portion which is displayed on the display screen, the user has to press-operate the operating surface in a state where the user touches the operating surface of the touch operation information output device. It is easy to perform an erroneous operation of the touch operation information output device and, because of this, the display device has a disadvantage of performing the displayed operation corresponding to the button display portion which was selected by mistake.